Do you get an extra attack? Is there a damage bonus to attacks? How does it work?

The baseline Two-Weapon Fighting rules can be found here: https://www.dndbeyond.com/sources/basic-rules/combat#TwoWeaponFighting
In brief when you take the Attack Action and attack with a Light weapon you can use your Bonus Action to make an attack with another Light weapon you are holding in your other hand.

For example a player could be holding a Dagger in each hand. With their Action the player uses the Attack Action to make an attack with the Dagger they are holding in their right hand. This satisfies the requirements for Two-Weapon Fighting and so now the player can use their Bonus Action to make an attack with the Dagger they are holding in their left hand.

*Edit* as for damage the Bonus Action attack granted by Two-Weapon Fighting does not get the normal ability modifier bonus to damage. So in the above example the Dagger attack that was made using the Attack Action does 1d4 + Strength/Dexterity modifier damage. But the Bonus Action Dagger attack just does 1d4 damage.

Also, be careful about building for two weapon. It takes your bonus action to do it, so it may be competing with other abilities and powers. Make sure you know what your character’s action economy is, so you’ll know if you actually use it. It often doesn’t work well in practice. 

Alright thanks.

I couldn’t use a normal weapon without the light property then use a light weapon? Like Rapier attack then Scimitar attack…

Without the Dual Wielder Feat, both weapons must have the light property. Since a rapier does not have the light property, you cannot use a rapier and a scimitar together for TWF unless you have the feat.

The Dual Wielder feat removes the light requirement from the wielded weapons, and with that feat then rapier + scimitar can be used for TWF.

Dual Wielder

You master fighting with two weapons, gaining the following benefits:

• You gain a +1 bonus to AC while you are wielding a separate melee weapon in each hand.
• You can use two-weapon fighting even when the one-handed melee weapons you are wielding aren't light.
• You can draw or stow two one-handed weapons when you would normally be able to draw or stow only one.

Quote from Fangeye >>

The baseline Two-Weapon Fighting rules can be found here: https://www.dndbeyond.com/sources/basic-rules/combat#TwoWeaponFighting
In brief when you take the Attack Action and attack with a Light weapon you can use your Bonus Action to make an attack with another Light weapon you are holding in your other hand.

For example a player could be holding a Dagger in each hand. With their Action the player uses the Attack Action to make an attack with the Dagger they are holding in their right hand. This satisfies the requirements for Two-Weapon Fighting and so now the player can use their Bonus Action to make an attack with the Dagger they are holding in their left hand.

*Edit* as for damage the Bonus Action attack granted by Two-Weapon Fighting does not get the normal ability modifier bonus to damage. So in the above example the Dagger attack that was made using the Attack Action does 1d4 + Strength/Dexterity modifier damage. But the Bonus Action Dagger attack just does 1d4 damage.

 O